Cold draught through AC sockets in new extension.

[drpepe]

As above - all 10 double sockets have the issue. Existing house is stone built c1901 and no draughty sockets.

Builder has completed the extension and is in process of installing the kitchen.

Construction is breezeblock with celotex in the cavity, rendered outside. Inside dotndab, and skimmed. Floor is concrete>celotex>chipboard>engineered floor.

The builder is going to investigate, but any thoughts on solutions for this, or implications for quality of the work?

 

[footprints]

My guess would be he has used a box sinker and it has punched through the light construction block into the cavity.
I had a point put into a breeze kitchen wall and it punched out part of the lounge wall the other side.
Should be easy to fix, but the boxes may have to come out to make good.

 

[drpepe]

Thanks. So he should have used shallower boxes?

What would be the proper way to sort it? (rather than a quick fix squirt of expanding foam)

 

[footprints]

In my case it was not the depth of the box but the box sinker is used with an SDS drill that drills a round hole then hammers it out into a square one, if you only have a thin bit of weak block behind the box recess it can just burst out the other side. Best bet is to see what is behind the box and decide then.

 

[footprints]

Of course it could simply be following up conduit alongside the wires from under floor.

 

[drpepe]

Of course it could simply be following up conduit alongside the wires from under floor.

From a quick chat with the builder, I think this is what he suspects.

In which case, would the best solution be some filler/foam in the conduit?

 

[r896neo]

No to foam. Expanding foam can eat the coating on electrical cabling in theory so shouldnt be used. Caulk would probably be most suitable.

 

[JohnD]

if there is a cavity behind, you can stuff it with mineral wool, which will insulate and block draughts, and I suppose you could use it in conduit though I frankly doubt it is the source. Caulk may be a good idea to seal small gaps.

The gap will be from the cavity, and there should be no cables in there, so you could inject foam if there is a big enough hole. Wrap the cables for protection until it has set, then cut away excess. You can get pink firestop foam if necessary.

 

[theprinceofdarkness]

Your builder has not installed the celotex properly. If it was installed properly (taped etc.) then the inside skin would be sitting in a draft free box.
Fill the holes in the boxes with foam and ask for a 100% rebate on the cost of the celotex. He has ruined the build.
Frank

 

[noseall]

I agree with the POD in that it is a quality issue. Some builders take steps to mitigate this very problem.

When we dab out a wall we make sure there can be no air travel behind the boards in particular around the boxes.

Dabbing

• noseall
• 12 Dec 2015

We apply a similar robust principle to any voids within a build i.e. Preventing air movement etc.